From what I've heard, the cradle will allow you to interface with the roof-mounted shark fin antenna, which substantially boosts signal strength. It also has a fan to help keep the iPhone relatively cool. But let me know if you notice an increase in your signal strength by just using the USB connection.

If your iPhone is getting hot, and you have rear climate control, set te temperature to low and close the vents... It gets the console pretty cold - cold enough to chill drinks